Important new work is presented by the authors on radiometrically dating the Bukit Piring intrusion and associated Arip Volcanics, as well as confirmation that widespread outcrops of Oligocene and Miocene clastic formations share a common sediment provenance. This valuable contribution is weakened by a poorly researched stratigraphic model that conflicts with much published work. The importance of good micropalaeontology is stressed in this review as without this tool the essential dimension of time is lost, and facies determinations are less reliable. These inputs are two of the three two components, along with space, that make stratigraphy a testable science under Walther's Law. © 2019 Elsevier B.V.